Microfluidic chip

Abstract

A microfluidic chip orients and isolates components in a sample fluid mixture by two step focusing, where sheath fluids compress the sample fluid mixture in a sample input channel in one direction, such that the sample fluid mixture becomes a narrower stream bounded by the sheath fluids, and by having the sheath fluids compress the sample fluid mixture in a second direction further downstream, such that the components are compressed and oriented in a selected direction to pass through an interrogation chamber in single file formation for identification and separation by various methods. The isolation mechanism utilizes external, stacked piezoelectric actuator assemblies disposed on a microfluidic chip holder, or piezoelectric actuator assemblies on-chip, so that the actuator assemblies are triggered by an electronic signal to actuate jet chambers on either side of the sample input channel, to jet selected components in the sample input channel into one of the output channels.

What is claimed is: 
     
       1. A method of sorting particles using a microfluidics-based flow cytometry apparatus, the method comprising:
 flowing a fluid sample comprising a plurality of particles suspended in the fluid sample into a channel of a microfluidic chip; 
 flowing a first sheath fluid flow and a second sheath fluid flow into the microfluidic chip; 
 intersecting the fluid sample with the first sheath fluid flow at a first intersection in the channel of the microfluidic chip thereby focusing the fluid sample while maintaining a laminar fluid flow of the fluid sample and the first sheath fluid flow; 
 intersecting the fluid sample and the first sheath fluid flow with the second sheath fluid flow at a second intersection in the channel of the microfluidic chip, thereby further focusing the fluid sample into a focused fluid flow and maintaining the laminar fluid flow of the fluid sample, the further focusing causing the plurality of particles suspended in the fluid sample to flow in approximately single file formation; 
 interrogating particles in the plurality of particles suspended in the fluid sample individually at an interrogation location in the channel of the microfluidic chip by the emission of electromagnetic radiation; 
 distinguishing the particles in the plurality of particles suspended in the fluid sample based on the interrogating; 
 sorting the particles in the plurality of particles suspended in the fluid sample based on the distinguishing step, the sorting comprising diverting a subset of the plurality of particles suspended in the fluid sample from the focused flow and into one of a plurality of output channels, wherein a cross-section and length of each of the plurality of output channels is maintained such that a volume of at least one output channel of the plurality of output channels is twice a volume of at least one other output channel of the plurality of output channels to provide a desired hydraulic resistance for the diverting of the subset of the plurality of particles suspended in the fluid sample; and 
 collecting, from the one of the plurality of output channels, the subset of the plurality of particles diverted from the focused flow. 
 
     
     
       2. The method of  claim 1 , wherein the emission of electromagnetic radiation is by an interrogation apparatus, the interrogation apparatus comprising:
 a light source configured to emit a light beam which illuminates and excites said plurality of particles suspended in the fluid sample from the focused flow. 
 
     
     
       3. The method of  claim 1 , further comprising:
 pumping the fluid sample by a pumping mechanism from a reservoir into said microfluidic chip; and 
 pumping said first sheath fluid flow and said second sheath fluid flow from a sheath fluid reservoir into said first intersection and second intersection of said microfluidic chip. 
 
     
     
       4. The method of  claim 3 , further comprising:
 controlling by a computer the pumping of the fluid sample, the first sheath fluid flow, and the second sheath fluid flow into the microfluidic chip. 
 
     
     
       5. The method of  claim 1 , wherein diverting the subset of the plurality of particles suspended in the fluid sample from the focused flow further comprises:
 deflecting by an actuator a flexible membrane when signaled by a detector operating on the microfluidic chip that a particle having a predetermined characteristic is detected in the channel. 
 
     
     
       6. The method of  claim 5 , wherein deflecting the flexible membrane creates a pressure pulse in a fluid flowing through the channel of the microfluidic chip. 
     
     
       7. The method of  claim 1 , further comprising expelling the subset of the plurality of particles diverted from the focused flow out of a first outlet of the one of the plurality of output channels. 
     
     
       8. The method of  claim 7 , further comprising expelling the focused flow out of a second outlet of another of the plurality of output channels. 
     
     
       9. The method of  claim 1 , further comprising cryopreserving the collected subset of the plurality of particles diverted from the focused flow. 
     
     
       10. A method of sorting cells using a microfluidics-based flow cytometry apparatus, the method comprising:
 obtaining a sample of live cells; 
 staining the sample of live cells with a dye in a media to obtain a fluid sample comprising a plurality of cells suspended in the fluid sample; 
 flowing the fluid sample comprising the plurality of cells suspended in the fluid sample into a channel of a microfluidic chip; 
 flowing a first sheath fluid flow and a second sheath fluid flow into the microfluidic chip; 
 intersecting the fluid sample with the first sheath fluid flow at a first intersection in the channel of the microfluidic chip thereby focusing the fluid sample while maintaining a laminar fluid flow of the fluid sample and the first sheath fluid flow; 
 intersecting the fluid sample and the first sheath fluid flow with the second sheath fluid flow at a second intersection in the channel of the microfluidic chip, thereby further focusing the fluid sample into a focused fluid flow and maintaining the laminar fluid flow of the fluid sample, the further focusing causing the plurality of cells suspended in the fluid sample to flow in approximately single file formation; 
 interrogating cells in the plurality of cells suspended in the fluid sample individually at an interrogation location in the channel of the microfluidic chip by the emission of electromagnetic radiation; 
 distinguishing the cells in the plurality of particles suspended in the fluid sample based on a physical characteristic of the cells identifiable by the interrogating; 
 sorting the cells in the plurality of cells suspended in the fluid sample based on the distinguishing step, the sorting comprising diverting a subset of the plurality of cells suspended in the fluid sample from the focused flow and into one of three output channels, wherein a cross-section and length of each of the output channels is maintained such that a volume ratio of the output channels is 2:1:2 or 1:2:1 to provide a desired hydraulic resistance for the diverting of the subset of the plurality of particles suspended in the fluid sample; and 
 collecting, from the one of the output channels, the subset of the plurality of cells diverted from the focused flow. 
 
     
     
       11. The method of  claim 10 , wherein the emission of electromagnetic radiation is by an interrogation apparatus, the interrogation apparatus comprising:
 a light source configured to emit a light beam which illuminates and excites the dye in said plurality of cells suspended in the fluid sample from the focused flow. 
 
     
     
       12. The method of  claim 10 , further comprising:
 pumping the fluid sample by a pumping mechanism from a reservoir into said microfluidic chip; and 
 pumping said first sheath fluid flow and said second sheath fluid flow from a sheath fluid reservoir into said first intersection and second intersection of said microfluidic chip. 
 
     
     
       13. The method of  claim 12 , further comprising:
 controlling by a computer the pumping of the fluid sample, the first sheath fluid flow, and the second sheath fluid flow into the microfluidic chip. 
 
     
     
       14. The method of  claim 10 , wherein diverting the subset of the plurality of cells suspended in the fluid sample from the focused flow further comprises:
 deflecting by an actuator a flexible membrane when signaled by a detector operating on the microfluidic chip that a cell having a predetermined characteristic is detected in the channel. 
 
     
     
       15. The method of  claim 14 , wherein deflecting the flexible membrane creates a pressure pulse in a fluid flowing through the channel of the microfluidic chip. 
     
     
       16. The method of  claim 10 , further comprising expelling the subset of the plurality of cells diverted from the focused flow out of a first outlet of the one of the output channels. 
     
     
       17. The method of  claim 16 , further comprising expelling the focused flow out of a second outlet of another of the output channels. 
     
     
       18. The method of  claim 10 , further comprising maintaining the collected subset of the plurality of cells diverted from the focused flow in a live state after the collecting. 
     
     
       19. The method of  claim 10 , further comprising cryopreserving the collected subset of the plurality of cells diverted from the focused flow.